| Redundancy design is of great significance to ensure the reliability of the protection system of the smart substation.The development of communication technology of smart substation provides the technical conditions for the realization of centralized protection.Based on the analysis of the typical redundancy structure of substations,this paper completes the design of integrated redundancy scheme of intelligent substation protection.And the scheme’s reliability is researched and discussed.This paper firstly introduces the structure of smart substation,focuses on the analysis of the hierarchical structure of the network in the station and the specific networking mode.Then this paper evaluates the characteristics and application scenarios of different networking schemes,and determines to use network sampling and network tripping mode.Based on analyzing the typical protection schemes of smart substation at present,the integrated redundancy scheme of smart substation protection is designed.The paper discusses the key issues such as the design of protection architecture,the protection configuration,and the mode of secondary wiring.Based on local protection system,the scheme integrates all or part of the protection functions into one or more substation protection devices,to form an economical,flexible,and reliable integrated protection system.However,there are some differences between the new scheme and the traditional protection scheme,especially the use of network sampling and network trip mode,which makes the factors affecting the reliability of relay protection more diversified.To compare the reliability of the integration redundancy protection scheme and the typical protection scheme,this paper firstly introduces the reliability evaluation index and modeling method.Based on the logic diagram method,the reliability model of the line protection,bus protection,and transformer protection is established.This model refinement to the component level,consider action logic inside the protection and the cooperate relationship between different protection.In the case of line fault and failure of protection element happen simultaneously,the reliability calculation method proposed by the paper can obtain the influence range of faults and the corresponding probability.Based on the typical 110 k V substation,this paper compares the four kinds of relay protection system implementation schemes including the typical protection scheme and integration redundancy scheme.The action result of the protection system was obtained through simulation calculation,and the results were analyzed and compared from the aspects of failure probability,failure reason,structural importance degree,and so on.The results show that the reliability of the integrated redundancy protection scheme is better than that of the typical simplex scheme.The integrated redundancy protection system scheme combines economy and reliability and can meet the protection system requirements of both110 k V and some 220 k V smart substations.The reliability analysis method proposed in this paper can be used to demonstrate the reliability of new protection design schemes and guide the planning and construction of the substation protection system. |
